Mechanical-energy influences to electrochemical phenomena in lithium-ion batteries

In lithium-ion batteries, Li ions usually infiltrate into the anode active material, which usually leads to the formation of Li compounds with expanding volumes. It is well known that the volume strain associated with dilatation/contraction at the intercalation/deintercalation cycles gradually deteriorates the electrode. The intention of this work devoting a simple Li/Sn battery system is to clearly show that such a mechanical strain accompanied by the formation of the Li-Sn compounds causes the following more fundamental phenomena: (i) the electrode potential tends to be lower than the value predicted from the chemical thermodynamics consideration, (ii) the kinetics rate of lithiation or delithiation is significantly retarded (i.e., much slower than expected from the diffusion of Li), and (iii) the electromotive force can be controlled by utilizing the elastic strain actively. Through this paper, we demonstrate the mechanical effects of such mechanical strain or energy on the electrochemical reaction with various experimental supports.